Age and mineralization origin of the Zhongshangou Au deposit, Zhangjiakou goldfield, North China: Constraints from molybdenite Re-Os age and sulfides S-Pb isotopes

Abstract

The Zhangjiakou goldfield, located in the northern North China Craton (NCC) margin, is a typical gold mineral province in China, containing over 67 gold deposits with 260 t gold reserve. However, gold mineralization age in this district has not been well constrained. Here, we integrate mineral paragenesis, molybdenite Re-Os age and in situ sulfides S and Pb isotopes from the Zhongshangou Te-rich Au deposit to constrain the timing and origin of gold and tellurium mineralization. Molybdenite Re-Os dating yielded a weighted average age of 381.7 ± 2.0 Ma (2σ, MSWD = 0.37, n = 7). Molybdenite has similar δ34S value (-12.9 to −8.5‰, n = 10) to other sulfide minerals (23 pyrite, 2 chalcopyrite and 2 bornite, δ34S = -13.6 to −5.6‰). Lead isotope compositions also show no difference among these sulfide minerals. Considering the mineral paragenesis and S-Pb isotopes, we suggest that molybdenite coprecipitated with gold, tellurides and other types of sulfides from the ore-forming fluids, and that the molybdenite Re-Os data could represent the timing of Zhongshangou gold and tellurium mineralization. New and published age data define a ca. 380 Ma Au-Te mineralization event for the Zhangjiakou goldfield. These Au deposits were genetically associated with the Devonian alkaline magmatism.